Support automated docz contents with stories

[transitive-bullshit]

Plugin option to insert one virtual mdx entry for each story "kind".

This should be the default behavior that may be disabled by a plugin config option.

See #4

Dependent on storybookjs/storybook#4649 and doczjs/docz#431

[transitive-bullshit]

One thing we'll want to support before closing this will be detecting if the version of docz or storybook installed is too old to have our updates.

For storybook, we should be able to work around the bugfix by adding some custom logic.

For docz, we should just bail and alert the user to upgrade.

[transitive-bullshit]

Current status:

• we support reliable storybook version detection for v3 vs v4
• for storybook v4, automated docz contents are supported dependent on feat(docz-core): updates to plugin hooks doczjs/docz#431
• for storybook v3, the build process is different and we'll need to figure this out

[MaluNoPeleke]

Does this plugin still work with Docz v2?

[transitive-bullshit]

@MaluNoPeleke I'm not sure, though I doubt it as things were pretty brittle and a lot changed with docz v2.

@jpeters5392 any idea on this?